Wafers are inspected for detecting defective wafers, in particular during and/or after their production. Usually, the inspection is carried out using a scanner which scans the wafers. Inspection devices are known, comprising a scanner, to which a wafer is supplied by means of a transport device, wherein the transport device comprises a wafer carrier—also called a wafer table or chuck —, inside which the wafer to be inspected is placed during inspection.
When inspecting the wafer, the result of the inspection depends with some known methods very much on a rotational angular alignment of the inspected wafer in the wafer carrier. So, in practical applications, the wafers are often supplied to the inspection device aligned by their rotational angle.
However, in some applications such a pre-alignment is not possible or non-economic. In these cases it is known to realise the wafer table in a rotatable version or to supply the wafer from the wafer store to a so-called pre-aligning device which is arranged separately from the inspection device.
German patent application DE 199 25 653 A1 shows a system for controlling the alignment of a semiconductor wafer, wherein the wafer can be taken out of a carrier by means of a wafer transport arm and can be transported to an alignment conversion unit. A rotatable wafer carrier known from German patent application DE 10 2009 026 187 A1 has a complex design and a complex movement inside the inspection device. A pre-aligning device known from US patent application US2002/0039436 A1 has amongst others the disadvantage that the wafer must cover an additional distance from the store to the pre-aligning device and from the pre-aligning device to the wafer table by means of a separate operational device which has in particular a negative effect on the achievable minimum duration of inspection.